This invention relates to semiconductor devices, and in particular, relates to semiconductor lasers having a diffusion barrier therein.
A semiconductor laser includes an active laser region composed of indium, gallium, arsenic, and phosphorous, for example, and two adjacent layers. One adjacent layer is a n-type semiconductor such as n-type indium phosphide, and the other adjacent layer is a p-type semiconductor such as zinc-doped indium phosphide. In order to form these layers, liquid phase epitaxy is used. Normally, growth temperatures range from about 670 degrees centigrade to about 600 degrees centigrade, and a slow cooling rate, about 0.3 degree centigrade per minute, is employed. When large amounts of zinc, such as 5 milligrams or more, is used to dope the p-type layer, zinc migrates thru the undoped active laser region into the n-type layer heterowall, thereby, placing an effective p-n junction in the n-type layer.
There currently exists, therefore, a need to achieve a higher acceptor concentration in the p-hetero layer and contacting layer surface.